在为二叉树实现add_node
和search
方法时,我收到RecursionError:超过最大递归深度
代码:
class TreeNode:
def __init__(self, value):
self.value = value
self.left = None
self.right = None
class BinaryTree:
def __init__(self, root=None):
self.root = root
def add_node(self, node, value):
node = self.root
if node is not None:
if not node.value:
node.value = value
elif not node.left:
node.left = value
elif not node.right:
node.right = value
else:
node.left = self.add_node(node.left, value)
else:
self.root = TreeNode(value)
def search(self, value):
node = self.root
found = False
while node is not None:
if node.value == value:
found = True
if node.left:
found = node.left.search(value)
if node.right:
found = found or node.left.search(value)
return found
def main():
binary_tree = BinaryTree()
binary_tree.add_node(binary_tree.root, 200)
binary_tree.add_node(binary_tree.root, 300)
binary_tree.add_node(binary_tree.root, 100)
binary_tree.add_node(binary_tree.root, 30)
binary_tree.traverse_inorder(binary_tree.root)
print(binary_tree.search(200))
if __name__ == '__main__':
main()
错误:
Traceback (most recent call last):
File ".\binary_tree_test20.py", line 51, in <module>
main()
File ".\binary_tree_test20.py", line 45, in main
binary_tree.add_node(binary_tree.root, 30)
File ".\binary_tree_test20.py", line 22, in add_node
node.left = self.add_node(node.left, value)
File ".\binary_tree_test20.py", line 22, in add_node
node.left = self.add_node(node.left, value)
File ".\binary_tree_test20.py", line 22, in add_node
node.left = self.add_node(node.left, value)
[Previous line repeated 995 more times]
RecursionError: maximum recursion depth exceeded
答案 0 :(得分:3)
这是我可以给你的补救方法。
class TreeNode:
def __init__(self, value):
self.value = value
self.left = None
self.right = None
def _add_node(node, value):
if not node.value:
node.value = value
elif not node.left:
node.left = TreeNode(value)
elif not node.right:
node.right = TreeNode(value)
else:
_add_node(node.left, value)
class BinaryTree:
# ...
def add_node(self, value):
node = self.root
if node is not None:
_add_node(node, value)
else:
self.root = TreeNode(value)
# ...
def main():
binary_tree = BinaryTree()
binary_tree.add_node(200)
binary_tree.add_node(300)
binary_tree.add_node(100)
binary_tree.add_node(30)
尽管我建议仅扩展TreeNode
的定义,而不定义BinaryTree
。
答案 1 :(得分:0)
由于没有使用node
参数,因此您将获得无限递归,而将其替换为self.root
。因此,当您递归时,您每次都会从根开始,并且永远不会结束。
此外,行node.left = self.add_node(node.left, value)
期望add_node
返回新节点,但是您的方法未返回任何内容。当更新现有节点时,它应该只返回修改后的节点。如果正在创建一个新节点,它将返回该节点。
def add_node(self, node, value):
if node is not None:
if not node.value:
node.value = value
elif not node.left:
node.left = value
elif not node.right:
node.right = value
else:
node.left = self.add_node(node.left, value)
return node
else:
return TreeNode(value)
您将这样调用此方法:
binary_tree.root = binary_tree.add_node(binary_tree.root, 30)